Abstract: An airtight tensionally stiff speaker diaphragm (i.e. being non-stretch, having a relatively high Young's modulus) which relies on tensile stiffness and air pressure to maintain its shape and produce sound can be extremely lightweight, a lighter spider is also described.

Abstract: Improved forms of negative stiffness are disclosed, also three general acoustic products are described herein, lower frequency speakers, lower frequency acoustic absorbers, and lower frequency acoustic blockers. the common denominator between these products is that they comprise a body of air, in an enclosure, that contracts and expands with every (lower frequency) wave, they may therefore utilize negative stiffness to counteract the (positive) stiffness of said body of air, making said body of air appear more compliant, and these enclosures may therefore comprise a non-stretch layer held taut by air pressure thus allowing for lighter and/or collapsible enclosures, particularly useful in slightly modified aircraft, said non-stretch layer may also serve as a diaphragm.

Abstract: This application relates to improvements in low-frequency sound energy absorption, and low-frequency sound energy reflection, utilizing something termed “negative stiffness” which can be used to counteract—positive-stiffness in a body of air, making said body of air more compliant, and thus more responsive to the changing pressures inherent in sound waves. This application also includes a stiff, yet light, structure/mechanism, including a diaphragm held taut by an air pressure difference, for gathering low frequency sound energy from a large area and directing it into a much smaller area, thus allowing a tiny damper to do all the work of a very large one, and thus allowing for very affective inflatable bass traps and resonators, it also allows for a small mechanism, that may comprise springs, weights, dampers, and levers, to be used to easily, manually, or automatically, adjust the impedance, e.g. allowing frequency, as well as Q, adjustments in a resonator/bass-trap.

Abstract: A rotating amusement device having two or more overlapping circle members which are independently rotatable with the overlapping sections being rotatable into the bodies of any or all of the overlapping circles or into a different overlapping of circles. The device can be utilized as a puzzle wherein various possible overlapping sections are differently colored or shaped and the object is to obtain a predetermined color combination or shape configuration. The circle members are comprised of interlocking elements with a peripheral frame holding the circles in such interlocking position while permitting the independent rotation of each of the circles. Increase in the number of overlapping circles adds to the complexity by increasing the number of possible permutations.